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US 6,839,208 B2Granted
Arc fault circuit interrupter recognizing arc noise burst patterns
AssigneePass & Seymour, Inc.
InventorsBruce F. Macbeth, Thomas N. Packard, Jeffrey C. Richards, James P. Romano
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Abstract
An arc fault circuit interrupter (AFCI) detects arc faults by identifying the various signature patterns of arc fault noise while rejecting arc mimicking noise from normal load phenomena.
Claims56
An arc fault detector for protecting electric power lines, comprising:
- a sensor coupled to said power lines for detecting broad band arc noise;
- a di/dt detector connected to said sensor for generating an output pulse having a time width associated with a time during which a pulse of broad band arc noise is above a predetermined threshold;
- a processor connected to said detector;
- a power line zero cross detector generating a time reference pulse for said processor;
- wherein said processor evaluates a width of said di/dt detector output pulse during each half wave following a zero cross pulse and opens a detection window for a first predetermined number of power line half cycles if, during any one power line half cycle, either (a) said width of said output pulse is equal to or exceeds a first predetermined interval, or (b) said width of said output pulse is equal to or exceeds two or more second predetermined intervals;
- wherein a length of said second predetermined interval is less than a length of said first predetermined interval;
- and
- wherein during said open detection window said processor ignores said output pulses for a rejection period lasting a second predetermined number of half cycles at a start of said window.
5 more elements
A method for detecting and interrupting arc faults in electric power lines, comprising the steps of:
- sensing random high frequency components in a load current of said electric power lines;
- producing pulse signals whose widths correspond to durations of said high frequency components;
- opening a window upon detection of a first pattern of said pulse signals;
- ignoring said pulse signals after said window is opened for a first predetermined interval;
- and
- interrupting load power in said electric power lines when one of said first pattern of pulse signals and a second pattern of pulse signals occurs after said step of ignoring while said window remains open.
3 more elements
A method for detecting and interrupting arc faults in electric power lines,comprising the steps of:
- sensing line frequency components and random high frequency components in a load current of said electric power lines;
- producing pulse signals whose widths correspond to durations of said high frequency components;
- opening a window upon detection of at least one predetermined first pattern of pulse signals;
- comparing a magnitude of a power line frequency against a threshold;
- tripping a circuit interrupter on said electric power lines if a second pattern of pulse signals occurs when said window is open and said power line frequency is below said threshold;
- and
- tripping said circuit interrupter if a third pattern of pulse signals occur when said window is open and said power line frequency is above said threshold.
4 more elements
An apparatus for detecting and interrupting arc faults in electric power lines, comprising:
- means for sensing random high frequency components in a load current of said electric power lines;
- means for producing pulse signals whose widths correspond to durations of said high frequency components;
- means for opening a window upon detection of a first pattern of said pulse signals;
- means for ignoring said pulse signals after said window is opened for a first predetermined interval;
- and
- means for interrupting load power in said electric power lines when one of said first pattern of pulse signals and a second pattern of pulse signals occurs after said step of ignoring while said window remains open.
3 more elements
An apparatus for detecting and interrupting arc faults in electric power lines, comprising:
- means for sensing line frequency components and random high frequency components in a load current of said electric power lines;
- means for producing pulse signals whose widths correspond to durations of said high frequency components;
- means for opening a window upon detection of at least one predetermined first pattern of pulse signals;
- means for comparing a magnitude of a power line frequency against a threshold;
- means for tripping a circuit interrupter on said electric power lines if a second pattern of pulse signals occurs when said window is open and said power line frequency is below said threshold;
- and
- means for tripping said circuit interrupter if a third pattern of pulse signals occur when said window is open and said power line frequency is above said threshold.
4 more elements
Dependencies are inferred from the claim text.